1. Field of the Invention
The present invention relates to heat treatment equipment for an object to be treated and the method of outputting the treatment""s exhaust gas. More specifically, the present invention relates to heat treatment equipment for an object to be treated and the method of outputting the exhaust gas resulting from the heat treatment, through exhaust holes in the equipment""s heat treatment chamber.
2. Prior Art
Recently, the demand for a device to be technically advanced and to be highly integrated is increasing. For this reason, the technique is remarkably developing that a pattern becomes minute and that the diameter of a semiconductor wafer becomes larger than it was. However, the minute pattern and the large diameter of the semiconductor wafer have made it difficult to ensure the equality of each size of the minute element pattern in the plane of the large diameter of the semiconductor wafer. This size accuracy is highly related to the reliability and yield of a semiconductor device. For example, a resist coating step in a photolithography step and various baking process as in a development step are given as one of the factors influencing the size accuracy of the element pattern. Especially, a chemical amplification resist is used as a resist material in a KrF excimer lithography step generally adopted to a mass production process for producing a pattern with a size of less than a quarter micrometer. The chemical amplification resist is an important parameter to decide the size by, especially, a baking condition.
Consequently, in the baking process in the process wherein the chemical amplification resist is used, it is necessary to keep the temperature distribution constant to ensure the size accuracy of the pattern in the plane of the large diameter of the semiconductor wafer. Therefore, it is also necessary for a heater inside a hot plate chamber to keep the temperature of the semiconductor wafer in the surface of the plane constant to control strictly the airflow inside the hot plate chamber.
Further recently, such various resist shrink techniques as the thermal shrink method are increasingly developed. However, it is necessary to control the baking temperature more strictly to introduce this kind of technique into an actual production line.
For example, a resist coating apparatus includes such plural units as a hot plate unit, a cooling unit and a coating unit. And a development apparatus includes such plural units as a hot plate unit, a cooling unit and a development unit.
Hereinafter, a schematic view of a conventional heat treatment equipment for an object to be treated is described with reference to FIGS. 9 and 10. It is to be noted that FIG. 9 is a sectional view showing the configuration of the conventional heat treatment equipment for an object to be treated and that FIG. 10 is a top view showing the configuration of the conventional heat treatment equipment for an object to be treated.
As shown in FIGS. 9 and 10, the conventional heat treatment equipment for an object to be treated has a heat treatment chamber (for example, a hot plate chamber) 604 for heating a semiconductor wafer (an object to be treated) 609. An up-and-down-movable support pin 606 carrying and mounting the semiconductor wafer 609 is set on a susceptor 605 set at the bottom of the heat treatment chamber 604. Also, a heater 607 heating the semiconductor wafer 609 for the baking process is set under the semiconductor wafer 609.
In addition, an opening and closing shutter 610 for opening and closing to carry the semiconductor wafer 609 into the heat treatment chamber 604 is set at the side of the heat treatment chamber 604. Further, an exhaust hole 601 is set on the upper part of the heat treatment chamber 604, and exhausted air 602 is released outside through a manual damper 612.
Next, a conventional heating treatment method for the object to be treated by the conventional heat treatment equipment for an object to be treated is to be described.
In the heating treatment (for example, a baking process) inside each treatment chamber (for example, a hot plate chamber), the opening and closing shutter 610 in the heat treatment chamber is opened, and a carrying robot, for example, transfers the semiconductor wafer 609 to the treatment chamber 604. At this time, the support pins 606 are waiting at an elevating location, and the carried semiconductor wafer 609 is placed on the support pins 606.
In the next process, the support pins 606 are sent down to place on a predetermined location for the heat treatment (for example, a baking process) for the semiconductor wafer 609. After that, the opening and closing shutter 610 is closed to achieve the baking process by heating the heater 607, and exhausting gas through an exhaust hole 601 set on the upper part of the heat treatment chamber 604.
However, when the exhaust hole is set on the upper part of the heat treatment chamber (on the upper side of the semiconductor wafer) as in the conventional heat treatment equipment (the hot plate apparatus), the airflow inside the heat treatment chamber is changed due to the differences of the location and diameter of the exhaust hole to make it difficult to keep the temperature distribution on the semiconductor wafer constant inside. For this reason, it becomes difficult to control the temperature accuracy in the plane of the semiconductor wafer strictly. Especially, the higher the exhaust pressure in the baking process becomes, the more deteriorated the equality of the temperature in the plane of the semiconductor wafer becomes.
Consequently, it is an important factor to control the airflow inside the hot plate to enhance the temperature accuracy inside the hot plate. However, since the preferable exhaust cannot be executed inside various baking furnaces and the turbulent airflow inside the furnace occurs, the equality of the temperature in the plane of the semiconductor wafer becomes deteriorated.
At this time, when the exhaust pressure is reduced to save the turbulent airflow inside the heat treatment chamber, the intended purpose of exhaust cannot be achieved because such a desorption element from the resist as a solvent and a monomer is not removed enough. For this reason, a desorption gas diffuses into the peripheral units to pollute the inside of each apparatus such as the resist coating apparatus, the development apparatus and a photolithography apparatus for the semiconductor wafer. This may cause pollution inside the clean room by the heat treatment equipment itself.
Therefore, an object of the present invention is to provide novel and improved heat treatment equipment for an object to be treated capable of removing the desorption gas effectively, and of ensuring the equality of the temperature in the plane of the object to be treated by controlling preferably the turbulent airflow inside the heat treatment chamber.
To achieve the above object in the present typical invention, there is provided heat treatment equipment (a heat treatment apparatus for an object to be treated comprising a heat treatment chamber having an opening and closing shutter for carrying the object to be treated, an exhaust airway formed along the periphery of the heat treatment chamber and conducting the exhausted air of the heat treatment chamber to an exhaust hole through the opening and closing shutter and an exhaust hole for releasing the exhausted air conducted from the exhaust airway outside the heat treatment chamber.
In the present invention as described above, the exhaust is achieved not by a direct exhaust from the heat treatment chamber but by an exhaust from the outside the heat treatment chamber through the opening and closing shutter during the baking process for the object to be treated (for example, a semiconductor wafer) in the heat treatment chamber (for example, a hot plate chamber). Therefore, in the heat treatment chamber, the turbulent airflow due to the exhaust does not occur which enhances the equality of the temperature in the plane of the object to be treated, and as a result, enhances the size accuracy of the element pattern. In addition, since the exhaust in the heat treatment chamber is under execution, the desorption gas of the object to be treated does not diffuse into the peripheral equipments and the like.